What the Type of Water You Have Does to Your Hair—and What to Do About It

Hard water vs. soft water—this is one of those boring topics you can go far in life without ever really figuring out (especially before you own a home/set down roots). And yet water hardness is kiiiind of a big deal when it comes to your hair. You can buy all the fancy conditioners and styling products you want only to have your shower water totally sabotage you. Here's what you need to know about hard water, soft water, and good hair.

Hard Water

What it is: Water that has a high concentration of dissolved minerals, especially calcium and magnesium, which leach into the water supply from rock.

You have it if: White chalky stuff periodically builds up on your shower head, soaps/shampoos don't lather super well, and glasses look cloudy when they come out of the dishwasher.

What it does to hair: "These [dissolved minerals], along with others such as iron, copper, lead, and manganese, stick to the surface of hair causing unwanted buildup, brittleness, and discoloration," says Joe Cincotta, Ph.D., executive vice president of product development for Color Wow. "Hair becomes dull and lifeless."

What to do about it: The best fix is to install a water filter on your shower head (whole-house versions are even better, but pricey). "The other is to use a chelating shampoo at least every third shampoo to strip away buildup," Cincotta says. These are also often marketed as clarifying shampoos; browse our picks in the shopping box below. "Some people use a diluted cider vinegar or a lemon/lime juice rinse because the acidic nature of these juices will help remove hard water buildup from hair," he adds. Always offset the drying effects of clarifying shampoos/rinses by doing a deep-conditioning treatment after. For everyday, Cincotta recommends sticking to very gentle and hydrating cleansing and styling products, like those designed for color-treated hair. If hard water has affected your hair color, no need to panic and totally redo it—just do a glaze, says hairstylist Edward Tricomi of Warren-Tricomi. "This re-pigmentizes the hair, and brings back its natural tones." (Click back to our recent post about the best at-home glosses and glazes if you want to DIY this.)

Soft Water

What it is: Water that has a very low amount of dissolved minerals, either naturally or because the water has been treated to soften it.

You have it if: You have none of the buildup issues listed above, and your tap water tastes sort of salty.

What it does to hair: Washing can be a challenge when water's very soft. "It takes longer to thoroughly cleanse hair of hairspray and other styling products, which results in product buildup on the scalp," salon owner and hairstylist Oscar Blandi tells us. "This is especially an issue if you have naturally oily or fine hair—leftover products remaining on the scalp weigh hair down and make it feel greasier."

What do do about it: Blandi's prescription for soft water-induced greasiness: Wash your hair three times per week, doing at least two lathers and finishing with a very small amount of conditioner. "It's critical to use a good shampoo that is sulfate- and paraben-free. Always take the time to check the ingredient list," he says. Volumizing/texturizing styling products will help offset limpness, but use them sparingly so there's less to shampoo away.